Forward displacement analysis of a redundant parallel manipulator by approximation algorithms

This paper presents the forward displacement analysis of an 8-PSS(prismatic-spherical-spherical)redundant parallel manipulator whose moving platform is linked to the base platform by eight kinemtic chains consisting of a PSS joint and a strut with fixed length.A general approximation algorithm is used to solve the problem.To avoid the extraction of root in the approximation process,the forward displacement analysis of the 8-PSS redundant parallel manipulator is transformed into another equivalent problem on the assumption that the strut is extensible while the slider is fixed.The problem is solved by a modified approximation algorithm which predicates that the manipulator will move along a pose vector to reduce the difference between the desired configuration and an instantaneous one,and the best movement should be with minimum norm and least quadratic sum.The characteristic of this modified algorithm is that its convergence domain is larger than that of the general approximation algorithm.Simulation results show that the modelified algorithm is general and can be used for the forward displacement analysis of the redundant parallel manipulator actuated by a revolute joint.

牵引、推拿、斜扳三要素并用治疗腰椎间盘突出症308例疗效分析

目的 探讨牵引加推拿斜扳复位治疗腰椎间盘突出症的作用机理 ,分析中医手法复位对提高疗效的作用。方法 用 ATA－Ⅱ D型牵引床纵轴牵引加中医正骨手法之一：推拿斜扳复位法。结果 牵引下加手法复位，治疗 308例，有效 300例，无效 8例，总有效率 97.4％。结论 ATA－Ⅱ D型牵引床加熟练复位手法，疗效确实，安全可靠，实用性强。